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<div class="titlepage"><div><div><h4 class="title">
<a name="asio.reference.async_write.overload4"></a><a class="link" href="overload4.html" title="async_write (4 of 6 overloads)">async_write (4
        of 6 overloads)</a>
</h4></div></div></div>
<p>
          Start an asynchronous operation to write a certain amount of data to a
          stream.
        </p>
<pre class="programlisting">template&lt;
    typename <a class="link" href="../AsyncWriteStream.html" title="Buffer-oriented asynchronous write stream requirements">AsyncWriteStream</a>,
    typename <a class="link" href="../DynamicBuffer.html" title="Dynamic buffer requirements">DynamicBuffer</a>,
    typename <a class="link" href="../CompletionCondition.html" title="Completion condition requirements">CompletionCondition</a>,
    typename <a class="link" href="../WriteHandler.html" title="Write handler requirements">WriteHandler</a>&gt;
<a class="link" href="../asynchronous_operations.html#asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span class="emphasis"><em>DEDUCED</em></span></a> async_write(
    AsyncWriteStream &amp; s,
    DynamicBuffer &amp;&amp; buffers,
    CompletionCondition completion_condition,
    WriteHandler &amp;&amp; handler,
    typename enable_if&lt; is_dynamic_buffer&lt; typename decay&lt; DynamicBuffer &gt;::type &gt;::value &gt;::type *  = 0);
</pre>
<p>
          This function is used to asynchronously write a certain number of bytes
          of data to a stream. The function call always returns immediately. The
          asynchronous operation will continue until one of the following conditions
          is true:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
              All of the data in the supplied dynamic buffer sequence has been written.
            </li>
<li class="listitem">
              The completion_condition function object returns 0.
            </li>
</ul></div>
<p>
          This operation is implemented in terms of zero or more calls to the stream's
          async_write_some function, and is known as a <span class="emphasis"><em>composed operation</em></span>.
          The program must ensure that the stream performs no other write operations
          (such as async_write, the stream's async_write_some function, or any other
          composed operations that perform writes) until this operation completes.
        </p>
<h6>
<a name="asio.reference.async_write.overload4.h0"></a>
          <span><a name="asio.reference.async_write.overload4.parameters"></a></span><a class="link" href="overload4.html#asio.reference.async_write.overload4.parameters">Parameters</a>
        </h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">s</span></dt>
<dd><p>
                The stream to which the data is to be written. The type must support
                the AsyncWriteStream concept.
              </p></dd>
<dt><span class="term">buffers</span></dt>
<dd><p>
                The dynamic buffer sequence from which data will be written. Although
                the buffers object may be copied as necessary, ownership of the underlying
                memory blocks is retained by the caller, which must guarantee that
                they remain valid until the handler is called. Successfully written
                data is automatically consumed from the buffers.
              </p></dd>
<dt><span class="term">completion_condition</span></dt>
<dd>
<p>
                The function object to be called to determine whether the write operation
                is complete. The signature of the function object must be:
</p>
<pre class="programlisting">std::size_t completion_condition(
  // Result of latest async_write_some operation.
  const asio::error_code&amp; error,

  // Number of bytes transferred so far.
  std::size_t bytes_transferred
);
</pre>
<p>
                A return value of 0 indicates that the write operation is complete.
                A non-zero return value indicates the maximum number of bytes to
                be written on the next call to the stream's async_write_some function.
              </p>
</dd>
<dt><span class="term">handler</span></dt>
<dd>
<p>
                The handler to be called when the write operation completes. Copies
                will be made of the handler as required. The function signature of
                the handler must be:
</p>
<pre class="programlisting">void handler(
  const asio::error_code&amp; error, // Result of operation.

  std::size_t bytes_transferred           // Number of bytes written from the
                                          // buffers. If an error occurred,
                                          // this will be less than the sum
                                          // of the buffer sizes.
);
</pre>
<p>
                Regardless of whether the asynchronous operation completes immediately
                or not, the handler will not be invoked from within this function.
                Invocation of the handler will be performed in a manner equivalent
                to using <code class="computeroutput">asio::io_context::post()</code>.
              </p>
</dd>
</dl>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2018 Christopher M. Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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